An Archdemon's Dilemma: How to Love Your Elf Bride (Manga) Volume 4 by Fuminori Teshima

After easily repelling the armored assailant who coveted the power of an Archdemon, Zagan finds she is actually a little girl, and a dragon! As punishment for attacking him, Zagan orders the little dragon to... help Nephy with her chores?
Meanwhile, Chastille finds herself in trouble for refusing to take part in Zagan's subjugation. A new Archangel arrives in town, rumored to be after the apostate Chastille's life and looking to crown Zagan as his 500th kill.